hmm. i'm inclined to go with a bigeminal accelerated junctional rhythm. ashman's doesn't seem right due to the regularity of the rhythm...as for VT, isn't the rate too slow? just curious and my 2 cents.

Looks to me like bidirectional tachycardia. This is a regular rhythm, so cannot be atrial fibrillation. Ashmann's phenomenon happens mostly in atrial fib or with premature atrial contractions. It happens if a beat comes directly after a previous long R-R interval; the refractory period after this long R-R interval is prolonged, and so the next beat, though supraventricular (a fib or PAC), is aberrant. These are all wide and regular beats but with alternating axes.

Congrats to all of you who recognized the regular wide complex rhythm with alternating axes which define bidirectional ventricular tachycardia. (Yes, it truely is a regular rhythm - print it out to see).

Of interest, this patient was NOT on digoxin. Note that both QRS morphologies seen in this tachycardia have a RBBB morphology (predominant R wave in V1) suggesting this arrhythmia arose from the left ventricular chamber.

The mechanism of this arrhythmia is controversial. Many <a href="http://content.onlinejacc.org/cgi/content/full/54/13/1189>believe</a> the rhythm is an automatic or triggered arrhythmia from two locations in separate portions of the distal conduction system (e.g., the left anterior and left posterior fascicles). Reentrant mechanisms have been proposed as well but the usual inability to overdrive pace this arrhythmia makes many feel the arrhythmia is more likely a triggered phenomenon.

In this patient's case, these tracings were recorded after the patient was placed on dobutamine for reduced LVEF (estimated EF 24%) following a transmyocardial laser revascularization procedure via a thorocotomy approach. Discontinuation of dobutamine helped decrease the frquency of the arrhythmia, but did not completely control it. Low-dose beta blockers and (later) Amiodarone were eventually successful at maintaining sinus rhythm.

About Me

Westby G. Fisher, MD, FACC is a board certified internist, cardiologist, and cardiac electrophysiologist (doctor specializing in heart rhythm disorders) practicing at NorthShore University HealthSystem in Evanston, IL, USA and is a Clinical Associate Professor of Medicine at University of Chicago's Pritzker School of Medicine. He entered the blog-o-sphere in November, 2005.
DISCLAIMER: The opinions expressed in this blog are strictly the those of the author(s) and should not be construed as the opinion(s) or policy(ies) of NorthShore University HealthSystem, nor recommendations for your care or anyone else's. Please seek professional guidance instead.